Summary: Behavioral/Systems/Cognitive
Macaque Parieto-Insular Vestibular Cortex: Responses to
Self-Motion and Optic Flow
Aihua Chen,1 Gregory C. DeAngelis,1,2 and Dora E. Angelaki1
1Department of Anatomy and Neurobiology, Washington University School of Medicine, St. Louis, Missouri 63110, and 2Department of Brain and Cognitive
Sciences, Center for Visual Science, University of Rochester, Rochester, New York 14627
The parieto-insular vestibular cortex (PIVC) is thought to contain an important representation of vestibular information. Here we
describe responses of macaque PIVC neurons to three-dimensional (3D) vestibular and optic flow stimulation. We found robust vestib-
ular responses to both translational and rotational stimuli in the retroinsular (Ri) and adjacent secondary somatosensory (S2) cortices.
PIVC neurons did not respond to optic flow stimulation, and vestibular responses were similar in darkness and during visual fixation.
Cells in the upper bank and tip of the lateral sulcus (Ri and S2) responded to sinusoidal vestibular stimuli with modulation at the first
harmonic frequency and were directionally tuned. Cells in the lower bank of the lateral sulcus (mostly Ri) often modulated at the second
harmonic frequency and showed either bimodal spatial tuning or no tuning at all. All directions of 3D motion were represented in PIVC,
with direction preferences distributed approximately uniformly for translation, but showing a preference for roll rotation. Spatiotem-
poral profiles of responses to translation revealed that half of PIVC cells followed the linear velocity profile of the stimulus, one-quarter
carried signals related to linear acceleration (in the form of two peaks of direction selectivity separated in time), and a few neurons
followed the derivative of linear acceleration (jerk). In contrast, mainly velocity-coding cells were found in response to rotation. Thus,
PIVCcomprisesalargefunctionalregioninmacaqueareasRiandS2,withrobustresponsesto3Drotationandtranslation,butisunlikely
to play a significant role in visual/vestibular integration for self-motion perception.
Introduction